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https://repo.dactyloidae.xyz/Dactyloidae/UXP.git
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edc8d83307
This is the reference implementation for the Alliance for Open Media's av1 video code. The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.
107 lines
3.2 KiB
C
107 lines
3.2 KiB
C
/*
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* Copyright (c) 2001-2016, Alliance for Open Media. All rights reserved
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*
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* This source code is subject to the terms of the BSD 2 Clause License and
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* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
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* was not distributed with this source code in the LICENSE file, you can
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* obtain it at www.aomedia.org/license/software. If the Alliance for Open
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* Media Patent License 1.0 was not distributed with this source code in the
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* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
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*/
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/* clang-format off */
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include "aom_dsp/bitwriter.h"
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#include "av1/common/odintrin.h"
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#include "av1/common/pvq.h"
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#include "pvq_encoder.h"
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static void aom_encode_pvq_split(aom_writer *w, od_pvq_codeword_ctx *adapt,
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int count, int sum, int ctx) {
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int shift;
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int rest;
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int fctx;
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if (sum == 0) return;
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shift = OD_MAXI(0, OD_ILOG(sum) - 3);
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if (shift) {
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rest = count & ((1 << shift) - 1);
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count >>= shift;
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sum >>= shift;
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}
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fctx = 7*ctx + sum - 1;
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aom_write_symbol_pvq(w, count, adapt->pvq_split_cdf[fctx], sum + 1);
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if (shift) aom_write_literal(w, rest, shift);
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}
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void aom_encode_band_pvq_splits(aom_writer *w, od_pvq_codeword_ctx *adapt,
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const int *y, int n, int k, int level) {
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int mid;
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int i;
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int count_right;
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if (n <= 1 || k == 0) return;
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if (k == 1 && n <= 16) {
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int cdf_id;
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int pos;
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cdf_id = od_pvq_k1_ctx(n, level == 0);
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for (pos = 0; !y[pos]; pos++);
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OD_ASSERT(pos < n);
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aom_write_symbol_pvq(w, pos, adapt->pvq_k1_cdf[cdf_id], n);
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}
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else {
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mid = n >> 1;
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count_right = k;
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for (i = 0; i < mid; i++) count_right -= abs(y[i]);
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aom_encode_pvq_split(w, adapt, count_right, k, od_pvq_size_ctx(n));
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aom_encode_band_pvq_splits(w, adapt, y, mid, k - count_right, level + 1);
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aom_encode_band_pvq_splits(w, adapt, y + mid, n - mid, count_right,
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level + 1);
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}
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}
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/** Encodes the tail of a Laplace-distributed variable, i.e. it doesn't
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* do anything special for the zero case.
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*
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* @param [in,out] enc range encoder
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* @param [in] x variable to encode (has to be positive)
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* @param [in] decay decay factor of the distribution in Q8 format,
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* i.e. pdf ~= decay^x
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*/
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void aom_laplace_encode_special(aom_writer *w, int x, unsigned decay) {
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int shift;
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int xs;
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int sym;
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const uint16_t *cdf;
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shift = 0;
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/* We don't want a large decay value because that would require too many
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symbols. */
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while (decay > 235) {
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decay = (decay*decay + 128) >> 8;
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shift++;
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}
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decay = OD_MINI(decay, 254);
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decay = OD_MAXI(decay, 2);
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xs = x >> shift;
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cdf = EXP_CDF_TABLE[(decay + 1) >> 1];
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OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "decay = %d", decay));
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do {
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sym = OD_MINI(xs, 15);
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{
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int i;
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OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "%d %d %d %d %d\n", x, xs, shift,
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sym, max));
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for (i = 0; i < 16; i++) {
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OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "%d ", cdf[i]));
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}
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OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "\n"));
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}
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aom_write_cdf(w, sym, cdf, 16);
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xs -= 15;
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} while (sym >= 15);
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if (shift) aom_write_literal(w, x & ((1 << shift) - 1), shift);
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}
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